The spice is right: Spanish saffron samples

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  • Published: Feb 15, 2016
  • Author: David Bradley
  • Channels: Chemometrics & Informatics
thumbnail image: The spice is right: Spanish saffron samples

Floral fingerprinting

The crimson stigma of the saffron flower is one of the oldest and most expensive spices in the world. (Credit: Consejo Regulador DOP Azafrán de La Mancha)

Scientists from the Czech Republic and Spain have used a new cheminformatics "fingerprinting" approach to check data from 44 commercial saffron products to confirm that more than half of products labelled as premium Spanish saffron contained spice from other regions and were thus labelled as such erroneously or fraudulently.

The history of saffron, the expensive yellow spice made from the stigma of Crocus sativus flowers, stretches back three millennia, although there is evidence that people were using it as a pigment in what is present-day northwest Iran some 50000 years ago. Today, the spice remains a popular food colouring and the variety from Spain is considered one of the world's most exquisite. As such, Spanish saffron attracts a higher price than other products and consequently many products are labelled fraudulently, with saffron from other countries adulterating the Spanish product.

"Over the past few years the media have been reporting this fraudulent activity, but up until now there were barely any analytical tools that could be used to detect said fraud." explains Josep Rubert of the University of Chemistry and Technology (UCT Prague, Czech Republic) and the University of Valencia (Spain). "So, we created a new strategy to determine the authenticity of saffron based on metabolomics or, in other words, the chemical fingerprints of foods."

Certified saffron

The Rubert and colleagues explain that their new technique allows them to define three types of saffron. The first being certified as having Protected Designation of Origin (PDO) from La Mancha or Aragon, Spain. The second grown and packaged in Spain, although not having the PDO certificate. The third classification being saffron packaged as 'Spanish saffron' but, despite its name, being of unknown origin. With these three classifications, scientists from the UCT Prague led by Jana Hajslova, where Rubert is a postdoctoral researcher, collected 44 commercial saffron samples in order to test the authenticity of these. The team provides details of their multivariate analysis of liquid chromatography high resolution tandem mass spectrometry data in the journal Food Chemistry. The first phase of the study consisted in identifying the metabolites or small molecules characteristic of saffron. The statistical analyses then revealed clear differences between the three classes of saffron defined by the team. The results show that more than 50% of the samples were fraudulent having been neither grown in nor packaged in Spain.

Tonnage discrepancy

"It is highly likely that lower quality saffron is purchased in other countries (such as Morocco, Iran and India according to our data) at a much lower price than in Spain, Rubert explains. The team says their approach "is a top-quality model that correctly classified 100% of these samples in addition to having the capacity to correctly categorise others (even if they are unknown and do not have a label) more than 85% of the time".

The best molecular markers for saffron identification are glycerophospholipids and their oxidised lipids. They have also observed that the saffron technology and processing play a crucial role, "specifically during the drying process, wherein transformation of the product is determined by the temperature at which the process is carried out. The place where the saffron originates also has an influence on the end product." They point out that saffron from La Mancha is usually dried by laying out the fresh stigmas over sieves that are placed next to a heat source such as a fire, hot coal, a stove or a brazier. Saffron dehydration happens with 30 minutes or so and as it is carried out at a temperature of about 70 degrees Celsius lipid oxidation is accelerated.

Castile-La Mancha produces a little under 3 tonnes of saffron each year and represented over 97% of Spanish production. And yet, Spain exports almost 36 tonnes of saffron! "The [saffron] came from other countries, such as Iran or Morocco," says Pedro Pérez of the Protected Designation of Origin Regulatory Body in La Mancha. He insists that: "That foreign saffron is brought to Spain and labelled as 'produced and packaged in Spain', which is true, but the label fails to indicate the saffron's true origin, meaning that the consumer does not have enough information to assess the product."

Related Links

Food Chem 2016, online: "Saffron authentication based on liquid chromatography high resolution tandem mass spectrometry and multivariate data analysis"

Article by David Bradley

The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.

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